KR20090098292A - Apparatus and method for enquiring information on channel condition cognitive radio wireless communication system - Google Patents

Abstract

An apparatus and a method for enquiring information on the channel condition of a cognitive radio based wireless communication system are provided to recognize the changes in channel states accurately by allowing a DB server to inform the time for inquiring the channel state information again. The initialization is confirmed(201), and a base station sets up the connection with a DB server(203). The base station transmits an inquiry message to the DB server(205), and confirms whether or not the response message to the inquiry is received from the DB server(207). The base station confirms the effective time information included in the response message(209), and performs spectrum sensing.

Description

Apparatus and method for requesting channel status information in a cognitive radio based wireless communication system {APPARATUS AND METHOD FOR ENQUIRING INFORMATION ON CHANNEL CONDITION COGNITIVE RADIO WIRELESS COMMUNICATION SYSTEM}

The present invention relates to a cognitive radio (CR) based wireless communication system, and more particularly, to an apparatus and method for requesting available channel information in a cognitive radio based wireless communication system.

As the wireless communication system develops, types of services to be provided in the wireless communication system are diversified. Moreover, high speed wireless data transmission technology is required to stably provide various high quality services. Various systems and techniques have been proposed to achieve high-speed wireless data transmission technology, but techniques for high-speed data transmission at a faster, lower cost are constantly being studied. In addition, the rapidly developing wireless communication system requires a separate frequency band due to coexistence with the existing technology. However, frequency resources are limited and most of the frequency resources are currently occupied by existing systems.

However, even a frequency resource occupied by a particular system, that frequency band is not always in use. Therefore, recently, a method of detecting a time interval in which a frequency resource is not used and using the frequency resource in the detected time interval has been considered. As described above, a radio communication system based on Cognitive Ratio (CR) is used in a system designed to perform radio communication by recycling frequency resources occupied by a specific system but temporarily not used. For example, there is a TV (TeleVision) band as a band in which frequency resources that are temporarily not used are frequently generated. Accordingly, standards are established in IEEE 802.22 to solve technical requirements and problems for performing wireless communication using the TV band without affecting the TV broadcasting system. have.

The cognitive radio-based wireless communication system should determine the transmission power and the operating frequency band so that interference to a licensed system does not occur. Accordingly, the cognitive radio-based wireless communication system can select an operation channel only after performing a procedure of recognizing a frequency band in use by a licensed system using a spectrum sensing function. have. In addition, if a signal of a licensed system is detected through continuous spectrum sensing while performing communication through the selected operating channel, the cognitive radio-based wireless communication system should no longer use the corresponding operating channel.

However, the spectrum sensing function does not guarantee accurate recognition of channel usage by a licensed system. Furthermore, in order to perform the spectrum sensing, signal detection and processing for a long time must be performed, and thus, the performance of the cognitive radio-based wireless communication system may be degraded. Accordingly, there is a need for an alternative for accurately recognizing whether a licensed system uses a channel in a cognitive radio based wireless communication system.

Accordingly, an object of the present invention is to provide an apparatus and method for recognizing whether a channel is used by a licensed system in a cognitive radio based wireless communication system.

Another object of the present invention is to provide an apparatus and method for identifying idle channel information using band scheduling information of a licensed system in a cognitive radio based wireless communication system.

Another object of the present invention is to provide an apparatus and method for inquiring channel status information to a DB (Data Base) storing band scheduling information of a licensed system in a cognitive radio based wireless communication system.

 It is still another object of the present invention to provide an apparatus and method for tracking channel usage information of a system with a changing license in a cognitive radio based wireless communication system.

Still another object of the present invention is to provide an apparatus and method for notifying time when channel state information is changed in a cognitive radio based wireless communication system.

According to a first aspect of the present invention for achieving the above object, a method of operation of a base station in a Cognitive Radio (CR) based wireless communication system, and stores the band scheduling information of the licensed system (licensed) Transmitting a query message for inquiring channel status information to a DB (Data Base) server, and receiving a response message including the channel status information and effective time information from the DB server; Characterized in that.

According to a second aspect of the present invention for achieving the above object, an operation method of a DB server that stores band scheduling information of a licensed system in a cognitive radio-based wireless communication system, for querying channel status information from a base station; When the inquiry message is received, the process of generating the channel status information to be provided to the base station, checking the valid time which is the time that the validity of the channel status information is terminated, and includes the channel status information and the valid time information And transmitting a response message.

According to a third aspect of the present invention for achieving the above object, a base station apparatus in a cognitive radio-based wireless communication system, the query for inquiring channel status information to the DB server that stores the band scheduling information of the licensed system And a processor for transmitting a message and a processor for checking the channel state information and the valid time information from the response message received from the DB server.

According to a fourth aspect of the present invention for achieving the above object, a DB server device that stores band scheduling information of a licensed system in a cognitive radio-based wireless communication system, queries for inquiring channel status information from a base station. When the message is received, the control unit for generating the channel state information to be provided to the base station, confirming the valid time which is the time when the validity of the channel state information is terminated, and a response message including the channel state information and the valid time information Characterized in that it comprises a communicator for transmitting.

In a cognitive radio-based wireless communication system, by using a DB (Data Base) having band scheduling information of a licensed system, it is possible to determine whether to use a correct channel of a licensed system. In particular, the DB informs the effective time of the channel condition information, so that the cognitive radio-based wireless communication system can more accurately recognize the channel condition change.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Hereinafter, a description will be given of a technique for recognizing channels available in a cognitive radio (CR) based wireless communication system. Hereinafter, the present invention will be described using an Orthogonal Frequency Division Multiplexing (OFDM) / Orthogonal Frequency Division Multiple Access (OFDMA) scheme as an example. The same applies to other wireless communication systems.

A schematic structure of a cognitive radio based wireless communication system according to the present invention is shown in FIG.

As shown in FIG. 1, a cognitive radio based wireless communication system according to the present invention includes a base station 110, consumer premise equipment (CPE) 120, and a data base (DB) server 130. It is intermingled with a licensed system.

The base station 110 and the CPEs 120 communicate through a wireless channel and have a spectrum sensing function. Accordingly, the base station 110 and the CPEs 120 recognize a band available through a spectrum sensing function, that is, a band not used by a licensed system, and then set an operation channel. . The base station 110 and the CPEs 120 communicate with each other through the operating channel.

In particular, according to the present invention, the base station 110 and the CPEs 120 is the channel occupancy information of the licensed system provided from the DB server 130 and the base station 110 and the CPEs 120 Minimize interference to the licensed system by using permissible effective isotropically radiared power (EIRP) information for each. The EIRP is a criterion for expressing output performance of a wireless communication system, and is a value obtained by combining transmitter output, antenna gain, and system loss.

That is, the DB server 130 may be configured to use band scheduling information of a licensed system, frequency band range used, transmission start / end time, geographical location of the transmitter, transmitter EIRP of the transmitter, and antenna related information of the transmitter (eg, antenna height). , At least one of information about an antenna directivity and a directional pattern), a service guarantee region, and a guaranteed signal to interference ratio (SIR) in the guaranteed region. The DB server 130 provides channel occupancy information and maximum allowed EIRP information of the licensed system according to the inquiry of the base station 110. In this case, the DB server 130 and the base station 110 communicate with each other according to a separate protocol, and the communication between the DB server 130 and the base station 110 is a backbone network. Wired communication via or wireless communication via wireless channel.

In detail, the base station 110 provides geographic location information of an object to be provided with channel state information according to a promised protocol. In this case, at least one of operating spectrum range information and antenna-related information for the object to be provided with the channel state information may be additionally provided to improve the accuracy of the EIRP calculation. In this case, the object to be provided with the information is one of the base stations 110 or the CPEs 120 existing in the cell of the base station 110. For example, the base station 110 transmits an inquiry message including the information as shown in Table 1 below for the channel state information query.

Name Description Database_type The value identifies the type of database for which the query is directed. E.g. : 0 = TV Incumbent Database 1 = Part 72 Incumbent Database Geo-loacation Information Geo-location of querying device. Other information of the device E.g, antenna information of the querying device.

Accordingly, after checking the idle channels, the DB server 130 calculates the maximum allowable EIRP of the object to receive the maximum allowable channel state information in each of the idle channels. In other words, the DB server 130 calculates an EIRP that can prevent interference with a licensed system. In this case, the DB server 130 manages the geographic location and transmission power information of the object currently operating in the cognitive radio-based wireless communication system, and calculates the EIRP in consideration of the sum of the interference caused by the plurality of objects. Here, the idle channels are identified based on a time point at which the inquiry / response between the base station 110 and the DB server 130 is made.

In addition, the DB server 130 checks the bandwidth usage scheduling of the licensed system and determines the time to update the currently provided idle channel information and the maximum allowable EIRP information for each idle channel. In other words, the DB server 130 determines the time that affects the transmission power determination and the operation channel selection of objects of the cognitive radio-based wireless communication system due to the change in the band usage situation of the licensed system.

After calculating the maximum allowed EIRP and determining the time to update the maximum allowed EIRP information, the DB server 130 according to the promised protocol, the idle channel list information, the maximum allowed EIRP information for each idle channel, the maximum The base station 110 provides the time information to update the allowed EIRP information. For example, the DB server 130 transmits a response message including the information as shown in Table 2 below.

Name Description Database_type The value identifies the type of database for which the query request was directed. E.g .: 0 = TV Incumbent Database 1 = Part 74 Incumbent Database Status The value indicates whether a response to query was successfully received. E.g. : SUCCESS, INVALID_REQUEST, TRANSACTION_EXPIRED Geo-location Information Geo-location of querying device. For (i = 1 to Number of Channels Avaliable, i ++) {Channel_Number Max_Transmit_EIRP} List of Available Channel Numbers and corresponding maximum transmit power allowed. Effective Time Effective time for the current EIRP values to be vaild.

Upon receiving the response message, the base station 110 transmits the idle channel list information and the maximum allowed EIRP information for each idle channel to the corresponding object. In addition, the base station 110 inquires again of the channel status information to the DB server 130 according to the time information to update the maximum allowable EIRP information, that is, the valid end time information of the maximum allowable EIRP information currently provided. In the following description, for convenience of explanation, the time to update the maximum allowed EIRP information and the valid end time of the currently provided maximum allowed EIRP information are referred to as an effective time.

As described above, when the base station 110 inquires the channel status information to the DB server 130, the kind of inquiry is divided into two types. The first is an independent query that arises from its own needs, and the second is a dependent query that arises from reaching valid time. If the base station 110 wants to inform the DB server 130 of the type of the inquiry, the base station 110 transmits an inquiry message including the information as shown in Table 3 below.

Name Description Database_type The value identifies the type of database for which the query is directed. E.g. : 0 = TV Incumbent Database 1 = Part 72 Incumbent Database Query Type The type of query: 0 = this is the first query from the device; 1 = this is a query for updating EIRP value as the effective time from last query is expiring; Geo-loacation Information Geo-location of querying device. Other information of the device E.g, antenna information of the querying device.

When the inquiry message as shown in Table 3 is used, the base station 110 may inquire about the channel state information to be changed before the valid time is reached. That is, even if the inquiry message is received before the validity time, the DB server 130 receiving the inquiry message as shown in Table 3 determines whether the received inquiry message is for updating the channel status information upon reaching the validity time. You can judge. For example, when the value of the 'Query Type' is 1, the DB server 130 recognizes that the received query message is for updating channel condition information according to the valid time. Accordingly, the DB server 130 predicts channel state information to be changed in the valid time included in the transmitted response message, and transmits a response message including the predicted channel state information to the base station 110. Accordingly, the base station 110 may acquire the channel state information to be changed before the change, and thus, the base station 110 may more efficiently respond to the change in the channel state.

Hereinafter, the present invention will be described in detail with reference to the drawings the operation and configuration of the base station and DB server to exchange the channel status information as described above. In the following description, a first embodiment of the present invention refers to an embodiment in which an inquiry message as shown in Table 1 is used, and a second embodiment of the present invention provides an inquiry message as shown in Table 3 below. Means an embodiment when used.

2 is a flowchart illustrating an operation procedure of a base station for acquiring channel state information required by the cognitive radio based wireless communication system according to the first embodiment of the present invention.

Referring to FIG. 2, the base station determines whether it is initialized in step 201. For example, the base station checks whether the transition from the power off state to the power on state.

If it is initialized, the base station proceeds to step 203 to establish a connection with the DB server. At this time, the communication between the base station and the DB server is wired communication or wireless communication, and is performed according to a protocol promised to each other.

After establishing the connection with the DB server, the base station proceeds to step 205 and transmits an inquiry message for inquiring channel status information required by the base station to the DB server. Here, the channel state information means an idle channel list not occupied by a licensed system and maximum allowable EIRP information for each idle channel of the base station. In this case, the query message may include geographic location information of the base station, and may further include at least one of operating spectrum range information and antenna related information of the base station. For example, the inquiry message is configured as shown in Table 1.

After transmitting the inquiry message, the base station proceeds to step 207 to check whether a response message for the inquiry is received from the DB server. That is, the base station checks whether a response message including idle channel list information, maximum allowed EIRP information per idle channel, and valid time information is received from the DB server. For example, the response message is configured as shown in Table 2.

If the response message is received, the base station proceeds to step 209 to check the valid time information included in the response message. In other words, the base station confirms the time when the validity of the channel state information included in the response message ends.

After checking the valid time, the base station proceeds to step 211 to perform spectrum sensing. That is, the base station determines whether a signal of a licensed system is detected in bands accessible through spectrum sensing.

After performing the spectrum sensing, the base station proceeds to step 213 and uses the idle channel list obtained from the DB server, the maximum allowable EIRP for each idle channel, and the spectrum sensing result to determine the transmission power of the operating channel and the operating channel. Decide In detail, the base station selects at least one channel among the channels included in the idle channel list and at which the signal of the licensed system is not detected as the operation channel. The base station then determines the transmit power so as not to exceed the maximum allowed EIRP of the selected channel.

After determining the operating channel and the transmit power, the base station proceeds to step 215 to communicate with the terminals in its cell. That is, the base station allocates resources in an operation channel to terminals in a cell and transmits and receives control information and traffic data. Here, the terminals have the same meaning as the CPEs 120 shown in FIG. 1, and the terminals described in the following description with reference to FIGS. 3 to 9 also have the same meaning as the CPEs.

Thereafter, the base station proceeds to step 217 and checks whether the valid time identified in step 209 has been reached. That is, the base station checks whether the current time is the valid time. If the valid time has been reached, the base station returns to step 205 and inquires again of the channel status information required by the DB server. In other words, the base station transmits an inquiry message as shown in Table 1 above.

On the other hand, if the valid time has not reached, the base station proceeds to step 219 and checks whether it is necessary to query the channel status information. For example, as a result of performing periodic spectrum sensing, when a signal of a licensed system is detected in an operating channel, the base station determines that it is necessary to query channel state information. In addition, whether the channel status information query is required may be determined by various events defined by a system operator.

If it is necessary to inquire the channel state information, the base station returns to step 205 and inquires of the channel state information necessary for itself to the DB server. In other words, the base station transmits an inquiry message having the configuration as shown in Table 1. On the other hand, if there is no need to query the channel state information, the base station returns to step 215 and performs communication with the terminals in the cell.

3 is a flowchart illustrating an operation procedure of a base station for acquiring channel state information necessary for a terminal in a cognitive radio based wireless communication system according to a second embodiment of the present invention.

Referring to FIG. 3, the base station determines whether an access request of a terminal occurs in step 301.

When the access request of the terminal occurs, the base station proceeds to step 303 to perform an entry procedure with the terminal. That is, the base station establishes a connection with the terminal by exchanging information for performing communication according to the standard of the system.

After performing the entry procedure, the base station proceeds to step 305 and checks whether information for channel status information query is received from the terminal. That is, the base station checks whether the information to be provided together when receiving the channel status information required by the terminal is received. For example, the information for querying the channel state information is at least one of geographic location information, operating spectrum range information, and antenna related information of the terminal.

When the information for the channel status information query is received, the base station proceeds to step 307 and transmits an inquiry message for querying the required channel status to the terminal to the DB server. Here, the channel state information means an idle channel list not occupied by a licensed system and maximum allowable EIRP information for each idle channel of the base station. In this case, the inquiry message may include geographic location information of the terminal received in step 305, and may further include at least one of operating spectrum range information and antenna related information of the terminal. For example, the inquiry message is configured as shown in Table 1.

After transmitting the inquiry message, the base station proceeds to step 309 and checks whether a response message for the inquiry is received from the DB server. That is, the base station confirms whether a response message including idle channel list information, maximum allowed EIRP information of the terminal for each idle channel, and valid time information is received from the DB server. For example, the response message is configured as shown in Table 2.

If the response message is received, the base station proceeds to step 311 and checks the valid time information included in the response message. In other words, the base station confirms the time when the validity of the channel state information included in the response message ends.

Subsequently, the base station proceeds to step 313 and transmits the channel state information received in step 309 to the terminal. In other words, the base station transmits the idle channel list information and the maximum allowed EIRP information of the terminal for each idle channel.

Thereafter, the base station proceeds to step 315 to communicate with terminals in its cell. That is, the base station allocates resources in an operation channel to terminals in a cell and transmits and receives control information and traffic data.

Thereafter, the base station proceeds to step 317 and checks whether the valid time identified in step 309 has been reached. That is, the base station checks whether the current time is the valid time. If the valid time has been reached, the base station returns to step 307 and inquires of the channel status information necessary for itself from the DB server. In other words, the base station transmits an inquiry message as shown in Table 1 above.

On the other hand, if the valid time has not reached, the base station proceeds to step 319 to determine whether it is necessary to query the channel status information. For example, as a result of performing periodic spectrum sensing, when a signal of a licensed system is detected in an operating channel, the base station determines that it is necessary to query channel state information. In addition, whether the channel status information query is required may be determined by various events defined by a system operator.

If it is necessary to inquire the channel state information, the base station returns to step 307 and inquires again of the channel state information for the terminal to the DB server. In other words, the base station transmits an inquiry message as shown in Table 1 above. On the other hand, if there is no need to query the channel state information, the base station returns to step 315 to communicate with the terminals in the cell.

4 illustrates an operation procedure of a DB server in a cognitive radio based wireless communication system according to an embodiment of the present invention.

Referring to FIG. 4, in step 401, the DB server checks whether an inquiry message for querying channel state information is received from the base station. In this case, the inquiry from the base station is performed by a promised protocol, and is performed through wire communication or wireless communication. In addition, at least one of geographical position information, operating spectrum range information, and antenna-related information of an object to be provided with channel state information is received together. For example, the inquiry message is configured as shown in Table 1.

When the channel state information is inquired, the DB server proceeds to step 403 to identify idle channels by referring to band scheduling information of a licensed system. That is, the DB server manages the band scheduling information of the licensed system, and checks whether the licensed system uses the band through the band scheduling information. Here, the idle channels are identified based on a time point at which the inquiry of the base station occurs.

After checking the idle channels, the DB server proceeds to step 405 to calculate the maximum allowable EIRP of the object to receive the channel state information for each idle channel. At this time, the DB server calculates the maximum allowable EIRP for each idle channel by using the geographical position of the object to receive the channel state information, the antenna-related information to prevent interference to the licensed system. In addition, the DB server manages geographic location and transmission power information of an object currently operating in a cognitive radio-based wireless communication system, and calculates a maximum allowable EIRP in consideration of the sum of interference caused by a plurality of objects.

In step 407, the DB server checks the valid time. That is, the DB server checks the bandwidth usage scheduling information and determines a time to update the currently provided idle channel information and the maximum allowable EIRP information for each idle channel. In other words, the DB server determines the time when the validity of the information generated in steps 405 and 407 ends due to the change in the bandwidth usage of the licensed system.

In step 409, the DB server transmits a response message including the idle channel list information, the maximum allowable EIRP information for each idle channel, and the valid time information. For example, the response message is configured as shown in Table 1.

FIG. 5 is a flowchart illustrating an operation procedure of a base station for acquiring channel state information required by the cognitive radio based wireless communication system according to the second embodiment of the present invention.

Referring to FIG. 5, the base station determines whether it is initialized in step 501. For example, the base station determines whether the transition from the power off state to the power on state.

If it is initialized, the base station proceeds to step 503 to establish a connection with the DB server. At this time, the communication between the base station and the DB server is wired communication or wireless communication, and is performed according to a protocol promised to each other.

After establishing the connection with the DB server, the base station proceeds to step 505 and transmits an inquiry message for inquiring channel status information required by the base station to the DB server. Here, the channel state information means an idle channel list not occupied by a licensed system, maximum allowable EIRP information for each idle channel of the base station, and valid time information. In this case, the query message may include geographic location information of the base station, and may further include at least one of operating spectrum range information and antenna related information of the base station. For example, the inquiry message is configured as shown in Table 3, and the inquiry type information included in the inquiry message is set to a value corresponding to the independent inquiry.

After transmitting the inquiry message, the base station proceeds to step 507 and checks whether a response message for the inquiry is received from the DB server. That is, the base station checks whether a response message including idle channel list information, maximum allowed EIRP information per idle channel, and valid time information is received from the DB server. For example, the response message is configured as shown in Table 2.

If the response message is received, the base station proceeds to step 509 and checks the valid time information included in the response message. In other words, the base station confirms the time when the validity of the channel state information included in the response message ends.

After checking the valid time, the base station proceeds to step 511 to perform the spectrum sensing. That is, the base station determines whether a signal of a licensed system is detected in bands accessible through spectrum sensing.

After performing the spectrum sensing, the base station proceeds to step 513 to determine the transmission power in the operating channel and the operating channel using the idle channel list obtained from the DB server, the maximum allowable EIRP for each idle channel, and the spectrum sensing result. Decide In detail, the base station selects at least one channel among the channels included in the idle channel list and at which the signal of the licensed system is not detected as the operation channel. The base station then determines the transmit power so as not to exceed the maximum allowed EIRP of the selected channel.

After determining the operating channel and the transmit power, the base station proceeds to step 515 to communicate with the terminals in its cell. That is, the base station allocates resources in an operation channel to terminals in a cell and transmits and receives control information and traffic data.

Thereafter, the base station proceeds to step 517 and again inquires of the channel status information required by the DB server before reaching the valid time identified in step 509. That is, in order to obtain updated channel state information, the base station transmits an inquiry message as shown in Table 3. In this case, the inquiry type information included in the inquiry message is set to a value corresponding to the dependent inquiry. In other words, the statement type information is set to a value corresponding to the query generated due to the proximity of the valid time.

After transmitting the inquiry message, the base station proceeds to step 519 and checks whether a response message is received from the DB server. In this case, the channel state information included in the response message is the channel state information after the validity time checked in step 509.

If the response message is received, the base station proceeds to step 521 and changes the channel condition to utilize the channel condition information included in the response message received in step 519. In other words, when the valid time determined in step 509 is reached, the base station performs an operation such as operation channel determination, transmission power determination, etc. using the channel state information included in the response message received in step 519, and the terminal. Communicate with them.

In the embodiment described with reference to FIG. 5, the response message received in step 519 also includes valid time information as in the response message received in step 507. Accordingly, the base station performs steps 509 and 517 according to the valid time information included in the response message received in step 519. In addition, independently of the channel status information query according to the valid time, when a predetermined event occurs, the base station queries for channel status information.

6 is a flowchart illustrating an operation procedure of a base station for acquiring channel state information required by a terminal in a cognitive radio based wireless communication system according to a second embodiment of the present invention.

Referring to FIG. 6, the base station determines whether an access request of a terminal occurs in step 601.

When the access request of the terminal occurs, the base station proceeds to step 603 to perform an entry procedure with the terminal. That is, the base station establishes a connection with the terminal by exchanging information for performing communication according to the standard of the system.

After performing the entry procedure, the base station proceeds to step 605 and checks whether information for channel status information query is received from the terminal. That is, the base station checks whether the information to be provided together when receiving the channel status information required by the terminal is received. For example, the information for querying the channel state information is at least one of geographic location information, operating spectrum range information, and antenna related information of the terminal.

When the information for the channel state information query is received, the base station proceeds to step 607 and transmits an inquiry message for inquiring the required channel state to the terminal to the DB server. Here, the channel state information means an idle channel list not occupied by a licensed system, maximum allowable EIRP information for each idle channel of the base station, and valid time information. In this case, the inquiry message may include geographic location information of the terminal received in step 605, and may further include at least one of operating spectrum range information and antenna related information of the terminal. For example, the inquiry message is configured as shown in Table 3, and the inquiry type information included in the inquiry message is set to a value corresponding to an independent inquiry.

After transmitting the inquiry message, the base station proceeds to step 609 and checks whether a response message for the inquiry is received from the DB server. That is, the base station confirms whether a response message including idle channel list information, maximum allowed EIRP information of the terminal for each idle channel, and valid time information is received from the DB server. For example, the response message is configured as shown in Table 2.

If the response message is received, the base station proceeds to step 611 to check valid time information included in the response message. In other words, the base station confirms the time when the validity of the channel state information included in the response message ends.

In step 613, the base station transmits the channel state information received in step 609 to the terminal. In other words, the base station transmits the idle channel list information and the maximum allowed EIRP information of the terminal for each idle channel.

Thereafter, the base station proceeds to step 615 to communicate with the terminals in its cell. That is, the base station allocates resources in an operation channel to terminals in a cell and transmits and receives control information and traffic data.

Thereafter, the base station proceeds to step 617 and again inquires of the terminal state information necessary for the channel to the DB server before reaching the valid time identified in step 611. That is, in order to obtain updated channel state information, the base station transmits an inquiry message as shown in Table 3. In this case, the inquiry type information included in the inquiry message is set to a value corresponding to the dependent inquiry. In other words, the inquiry type information is set to a value corresponding to the inquiry generated by approaching the valid time.

After transmitting the inquiry message, the base station proceeds to step 619 and checks whether a response message is received from the DB server. In this case, the channel state information included in the response message is channel state information after the validity time checked in step 611.

When the response message is received, the base station proceeds to step 621 and uses the channel condition information included in the response message received in step 619 after changing the channel condition. In other words, when the valid time determined in step 611 is reached, the base station performs an operation such as operation channel determination, transmission power determination, etc. using the channel state information included in the response message received in step 619, and the terminal. Communicate with them.

In the embodiment described with reference to FIG. 6, the response message received in step 619 also includes valid time information as in the response message received in step 609. Accordingly, the base station performs steps 611 and 617 according to the valid time information included in the response message received in step 619. In addition, independently of the channel status information query according to the valid time, when a predetermined event occurs, the base station queries for channel status information.

7 illustrates an operation procedure of a DB server in a cognitive radio based wireless communication system according to an embodiment of the present invention.

Referring to FIG. 7, the DB server checks whether an inquiry message for querying channel state information is received from the base station in step 701. In this case, the inquiry from the base station is performed by a promised protocol, and is performed through wire communication or wireless communication. In addition, at least one of geographical position information, operating spectrum range information, and antenna-related information of an object to be provided with channel state information is received together. For example, the inquiry message is configured as shown in Table 3.

If the inquiry message is received, the DB server proceeds to step 703 and checks whether the inquiry message is an inquiry message based on a valid time proximity. That is, the DB server checks whether the inquiry type information included in the inquiry message is a value corresponding to an independent query or a value corresponding to a dependent query.

If the inquiry message is not an inquiry message based on the proximity of the valid time, the DB server proceeds to step 705 to identify the current idle channels by referring to the band scheduling information of the licensed system. That is, the DB server manages the band scheduling information of the licensed system, and checks whether the licensed system uses the band through the band scheduling information.

After checking the current idle channels, the DB server proceeds to step 707 to calculate the maximum allowable EIRP of the object to receive the channel state information for each idle channel. At this time, the DB server calculates the maximum allowable EIRP for each idle channel by using the geographical position of the object to receive the channel state information, the antenna-related information to prevent interference to the licensed system. In addition, the DB server manages geographic location and transmission power information of an object currently operating in a cognitive radio-based wireless communication system, and calculates a maximum allowable EIRP in consideration of the sum of interference caused by a plurality of objects.

In step 709, the DB server checks the valid time. That is, the DB server checks the bandwidth usage scheduling information, and determines the time to update the idle channel information generated in steps 705 and 707 and the maximum allowable EIRP information for each idle channel. In other words, the DB server determines the time when the validity of the information generated in steps 705 and 707 is terminated due to the change in the bandwidth usage of the licensed system.

Thereafter, the DB server proceeds to step 711 and transmits a response message including the idle channel list information, the maximum allowed EIRP information for each idle channel, and the valid time information generated in steps 705 to 709. For example, the response message is configured as shown in Table 2.

In step 703, if the query message is a query message based on the proximity of the valid time, the DB server proceeds to step 713 to check the idle channels after changing the channel state by referring to the band scheduling information of the licensed system. That is, the DB server checks idle channels after the validity time of the channel state information recently provided to the object corresponding to the geographic location information included in the query message received in step 701.

After checking the idle channels after the channel state change, the DB server proceeds to step 715 to calculate an expected maximum allowed EIRP of the object to receive the channel state information for each idle channel. At this time, the DB server calculates the maximum allowable EIRP for each idle channel, which is expected to prevent interference to a licensed system, by using the geographical position of the object to receive the channel state information and the antenna related information. In addition, the DB server manages geographic location and transmission power information of an object currently operating in a cognitive radio-based wireless communication system, and calculates a maximum allowable EIRP in consideration of the sum of interference caused by a plurality of objects.

In step 717, the DB server checks the valid time. That is, the DB server checks the bandwidth usage scheduling information, and determines the time to update the idle channel information generated in steps 713 and 715 and the maximum allowable EIRP information for each idle channel expected. In other words, the DB server determines the time when the validity of the information calculated in steps 713 and 715 ends because the band usage situation of the licensed system is changed.

In step 719, the DB server transmits a response message including the idle channel list information generated in steps 713 to 717, the maximum allowable EIRP information for each idle channel, and the valid time information. For example, the response message is configured as shown in Table 2.

8 is a block diagram of a base station in a cognitive radio based wireless communication system according to an exemplary embodiment of the present invention.

As shown in FIG. 8, the base station includes a DB communication unit 802, a DB protocol processor 804, a spectrum sensor 806, a message processor 808, a data buffer 810, a wireless communication unit 812, and a control unit. 814.

The DB communicator 802 provides an interface for communicating with a DB server. That is, the DB communication unit 802 performs a conversion function between the information bit string and the transmission / reception signal according to the communication method between the base station and the DB server. However, when wireless communication is performed between the base station and the DB server, the DB communication unit 802 includes an antenna.

The DB protocol processor 804 generates and interprets a message according to a protocol used between the base station and the DB server. For example, the DB protocol processor 804 generates a query message for requesting channel status information from the DB server. Here, the query message may include geographic location information of an object to which the channel condition information is to be provided, and may further include at least one of operating spectrum range information and antenna related information. For example, the inquiry message is configured as shown in <Table 1> or <Table 3>. The DB protocol processor 804 interprets the response message including the channel state information received from the DB server. Here, the response message includes idle channel list information, maximum allowed EIRP information for each idle channel, and valid time information. For example, the response message is configured as shown in Table 2.

The spectrum sensor 806 checks whether a signal of a licensed system is detected in all accessible bands. The spectrum sensor 806 notifies the control unit 814 of the detection result. The message processor 808 generates and interprets control messages exchanged with terminals in the cell. For example, the message processor 808 generates and interprets messages promised to each other for an initial access procedure of the terminal, and generates a map (MAP) message for informing the terminal of resource allocation information. In addition, the message processor 808 generates a message for transmitting the channel status information requested by the terminal.

The data buffer 810 temporarily stores data exchanged with the terminals, and outputs the stored data under the control of the controller 814. The wireless communication unit 812 provides an interface for performing communication with the terminals. For example, the radio 812 converts the transmitted bit string into complex symbols by encoding and modulating the transmission bit stream. The wireless communication unit 812 maps the complex symbols to subcarriers, converts the complex symbols into a time domain signal through an inverse fast fourier transform (IFFT) operation, and then inserts a CP (Cyclic Prefix) to baseband OFDM symbols. Configure Thereafter, the wireless communication unit 812 converts the baseband OFDM symbol into a radio frequency (RF) band signal of an operating channel and then transmits the signal through an antenna.

The controller 814 controls the overall operation of the base station. That is, the controller 814 provides information necessary for the operation of the other blocks and controls the operation of the other blocks. For example, the controller 814 determines an operating channel for communication with terminals in a cell, and determines transmission power. In other words, the controller 814 determines an operating channel and a transmission power in the operating channel using the idle channel list, the maximum allowable EIRP for each idle channel, and the spectrum sensing result. In detail, the controller 814 selects at least one channel among the channels included in the idle channel list and for which a signal of a licensed system is not detected as an operation channel. The controller 814 determines the transmission power so as not to exceed the maximum allowable EIRP of the selected channel. The controller 814 controls the transmission / reception RF band of the wireless communication unit 812.

In addition, when querying the channel status information to the DB server, the controller 814 provides the location information of the object to receive the channel status information to the DB protocol processor 804. In particular, the control unit 814 inquires again the channel status information according to the valid time information confirmed through the response message. That is, the query timer 816 triggers an inquiry of the channel condition information according to the valid time information, and the controller 816 requests the channel object information necessary for the object according to the triggering of the query timer 816. The DB protocol processor 804 is controlled to generate a query message. In addition, when various events defined by a system operator occur in addition to the triggering by the query timer 816, the controller 814 inquires about the channel status information. For example, one of the various events is a situation where a signal from a licensed system is detected on an operating channel.

Here, the operation of the control unit 814 and the DB protocol processor 804 will be described separately according to an embodiment of the present invention.

According to the first embodiment of the present invention, that is, when an inquiry message as shown in Table 1 is used, the inquiry timer 816 triggers an inquiry of the channel state information when the valid time is reached. Accordingly, the controller 814 controls the DB protocol processor 804 to generate the inquiry message, and the DB protocol processor 804 generates the inquiry message as shown in Table 1 below. In this case, the control unit 814 provides the geographic location information of the object to receive the channel status information to the DB protocol processor 804, the DB protocol processor 804 is the geographic location provided from the control unit 814 Create a query message that contains the information.

According to the second embodiment of the present invention, that is, when an inquiry message as shown in Table 3 is used, the inquiry timer 816 triggers an inquiry of the channel state information before the valid time is reached. . In this case, the difference between the triggering time of the query timer 816 and the valid time varies according to a specific embodiment of the present invention. Accordingly, the controller 814 controls the DB protocol processor 804 to generate the inquiry message, and the DB protocol processor 804 generates the inquiry message as shown in Table 3 below. In this case, the control unit 814 provides the geographic location information of the object to receive the channel status information to the DB protocol processor 804, the DB protocol processor 804 is the geographic location provided from the control unit 814 Create a query message that contains the information. In addition, the control unit 814 informs the DB protocol processor 804 of the type of inquiry, and the DB protocol processor 804 sets the type of inquiry information included in the inquiry message according to the type of the inquiry. In other words, when a query is generated due to the proximity of the valid time, the DB protocol processor 804 sets the statement type information to a value corresponding to the dependent query. Alternatively, when a query is generated due to a previously scheduled event or initialization of the base station, the DB protocol processor 804 sets the type of query information to a value corresponding to an independent query.

9 is a block diagram of a DB server in a cognitive radio based wireless communication system according to an exemplary embodiment of the present invention.

As shown in FIG. 9, the DB server includes a base station communication unit 902, a protocol processor 904, a band scheduling information manager 906, a control unit 908, and an EIRP calculator 910.

The base station communication unit 902 provides an interface for communicating with a base station. That is, the base station communication unit 902 performs a function of converting an information bit string and a transmission / reception signal according to a communication method between the DB server and the base station. However, when wireless communication is performed between the DB server and the base station, the base station communication unit 902 includes an antenna.

The protocol processor 904 generates and interprets a message according to a protocol used between the DB server and the base station. For example, the protocol processor 904 interprets an inquiry message about channel condition information received from the base station. Here, the query message may include geographic location information of an object to which the channel condition information is to be provided, and may further include at least one of operating spectrum range information and antenna related information. For example, the inquiry message is configured as shown in <Table 1> or <Table 3>. The protocol processor 904 then generates a response message to be sent to the base station as a response to the query message. Here, the response message includes idle channel list information, maximum allowed EIRP information for each idle channel, and valid time information. For example, the response message is configured as shown in Table 2.

The band scheduling information manager 906 stores band scheduling information of a licensed system and provides the band scheduling information to the controller 908. That is, the band scheduling information manager 906 manages information indicating which band of channels is used by the licensed system. In addition, the band scheduling information manager 906 stores geographic location information about a licensed system.

The controller 908 controls the overall operation of the DB server. That is, the controller 908 provides information necessary for the operation of the other blocks and controls the operation of the other blocks. For example, the controller 908 provides the EIRP calculator 910 with the geographic location information of the object requiring the EIRP information and the information of the idle channel, and the protocol processor 904 with the EIRP calculator 910. Provide the maximum allowable EIRP value calculated by In particular, when inquiring channel status information from the base station, the controller 908 refers to the band scheduling information to check the valid time. That is, the controller 908 checks the time to update the idle channel information to be provided through the response message to the query and the maximum allowable EIRP information for each idle channel. In other words, the controller 908 checks the time when the validity of the information to be included in the response message ends. The controller 908 informs the protocol processor 904 of the valid time so as to generate a response message including the valid time information.

The EIRP calculator 910 calculates the maximum allowable EIRP for each idle channel at the geographical location provided from the controller 908. In this case, the EIRP calculator 910 calculates the maximum allowable EIRP for each idle channel to prevent interference with a licensed system by using the geographical position and antenna-related information. In this case, the EIRP calculator 910 manages geographic location and transmission power information of an object currently operating in a cognitive radio-based wireless communication system, and calculates a maximum allowable EIRP in consideration of the sum of interference caused by a plurality of objects. do.

Herein, operations of the protocol processor 904, the controller 908, and the EIRP calculator 910 will be described according to embodiments of the present invention.

According to the first embodiment of the present invention, that is, when the inquiry message as shown in Table 1 is used, the protocol processor 904 checks the geographic location information included in the inquiry message received from the base station, The geographical location information is provided to the controller 908. After checking the current idle channels, the controller 908 provides the EIRP calculator 910 with information of the current idle channels and the geographic location information. Accordingly, the EIRP calculator 910 calculates the maximum allowable EIRP for each idle channel in the geographical location.

According to the second embodiment of the present invention, that is, when the inquiry message as shown in Table 3 is used, the protocol processor 904 is the geographic location information and the inquiry type information included in the inquiry message received from the base station Confirm the information and provide the geographical location information and the inquiry type information to the controller 908. The controller 908 determines at what point of time channel condition information is to be generated according to the inquiry type information. If the query information is a value corresponding to an independent query, the controller 908 determines to generate current channel state information. On the other hand, if the query information is a value corresponding to a dependent query, that is, a query generated by approaching the valid time, the controller 908 is after the valid time of the channel state information that was recently provided to the object corresponding to the geographic location information. It is determined to generate the channel status information of the. Accordingly, the controller 908 identifies the idle channels at the determined time point, and provides information on the idle channels and the geographical location information identified by the EIRP calculator 910. Accordingly, the EIRP calculator 910 calculates the maximum allowable EIRP for each idle channel in the geographical location.

In the above-described embodiments, the DB server induces the channel state information re-inquiry of the base station by providing the valid time information to the base station. In this case, the valid time information is recognized for the purpose of indicating the end time of validity of the channel state information provided together. If the valid time information is expressed as next query time information, the next query time information is recognized for the purpose of indicating a time for performing the next query. That is, the next inquiry time information may be recognized as information for actively inducing the inquiry operation of the base station compared to the valid time information. Therefore, even if the valid time information is replaced with the next query time information, it is obvious that it is included in the scope of the present invention.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

1 is a diagram illustrating a schematic configuration of a cognitive radio (CR) based wireless communication system according to the present invention;

FIG. 2 is a diagram illustrating an operation procedure of a base station for acquiring channel state information required by the cognitive radio based wireless communication system according to the first embodiment of the present invention; FIG.

3 is a flowchart illustrating an operation procedure of a base station for acquiring channel state information required by a terminal in a cognitive radio based wireless communication system according to a first embodiment of the present invention;

4 is a diagram illustrating an operation procedure of a DB (Data Base) server in a cognitive radio based wireless communication system according to a first embodiment of the present invention;

FIG. 5 is a flowchart illustrating an operation procedure of a base station for acquiring channel state information required by the cognitive radio based wireless communication system according to the second embodiment of the present invention; FIG.

6 is a flowchart illustrating an operation procedure of a base station for acquiring channel state information required by a terminal in a cognitive radio based wireless communication system according to a second embodiment of the present invention;

7 is a diagram illustrating an operation procedure of a DB server in a cognitive radio based wireless communication system according to a second embodiment of the present invention;

8 is a block diagram of a base station in a cognitive radio based wireless communication system according to an embodiment of the present invention;

9 is a block diagram of a DB server in a cognitive radio based wireless communication system according to an embodiment of the present invention.

Claims (29)

In the operation method of a base station in a Cognitive Radio (CR) based wireless communication system, Transmitting a query message for inquiring channel status information to a DB (Data Base) server that stores band scheduling information of a licensed system; Receiving a response message including the channel state information and effective time information from the DB server. The method of claim 1, And when the valid time is reached, inquiring the channel status information back to the DB server. The method of claim 2, The query message may include at least one of type information of the DB server, geographical position information of an object to which the channel condition information is to be provided, operating spectrum range information, and antenna related information. The method of claim 1, Querying the channel status information again with the DB server before the valid time is reached. The method of claim 4, wherein The inquiry message may include the type information of the DB server, the geographical position information of the object to which the channel condition information is to be provided, the operation spectrum range information, the antenna related information, and the inquiry generated when the inquiry message reaches the valid time. And at least one of the type of query information indicating whether or not the purpose of the request. The method of claim 1, The object to be provided with the channel state information is characterized in that the base station itself or one of the terminals located in the cell. The method of claim 1, The channel status information includes at least one of an idle channel list not occupied by the licensed system and maximum allowed effective isotropically radiared power (EIRP) information for each idle channel. The method of claim 7, wherein The response message may include at least one of type information of the DB server, status information indicating a state of a query, geographical position information of a target to be provided with channel status information, an idle channel list, maximum allowed EIRP information for each idle channel, and valid time information. A method comprising one. In a method of operating a DB (Data Base) server that stores band scheduling information of a licensed system in a Cognitive Radio (CR) based wireless communication system, Generating a channel condition information to be provided to the base station when an inquiry message for inquiring channel condition information is received from the base station; Checking an effective time which is a time at which the validity of the channel condition information ends; And transmitting a response message including the channel condition information and the valid time information. The method of claim 9, The process of confirming the valid time, And identifying the time when the band usage status of the licensed system is changed by referring to the band usage scheduling information. The method of claim 9, The process of generating the channel state information, Identifying at least one idle channel with reference to band scheduling information of the licensed system; And calculating a maximum allowable effective isotropically radiated power (EIRP) of an object to receive the channel state information for each of the at least one idle channel. The method of claim 11, Confirming the inquiry type information included in the inquiry message before generating the channel status information; And determining at which point of time the channel situation type is to be generated according to the inquiry type information. The method of claim 11, Determining at which point in time the channel situation type is generated, When the inquiry type information is a value corresponding to the dependent inquiry, determining to generate channel condition information after a valid time of the channel condition information recently provided to the object corresponding to the geographic location information included in the inquiry message; , And if the inquiry type information is a value corresponding to an independent inquiry, determining to generate channel state information at the time when the inquiry message is received. The method of claim 8, The response message may include at least one of type information of the DB server, status information indicating a state of a query, geographical position information of a target to be provided with channel status information, an idle channel list, maximum allowed EIRP information for each idle channel, and valid time information. Characterized in that it comprises one. In a base station apparatus in a Cognitive Radio (CR) based wireless communication system, A communicator for transmitting an inquiry message for inquiring channel status information to a DB (Data Base) server that stores band scheduling information of a licensed system; And a processor for checking the channel state information and the effective time information from the response message received from the DB server. The method of claim 15, And a controller for inquiring again of the channel status information to the DB server when the valid time is reached. The method of claim 16, The query message may include at least one of type information of the DB server, geographical position information of an object to which the channel condition information is to be provided, operating spectrum range information, and antenna related information. The method of claim 15, And a control unit which inquires again of the channel status information to the DB server before reaching the valid time. The method of claim 18, The inquiry message may include the type information of the DB server, the geographical position information of the object to which the channel condition information is to be provided, the operation spectrum range information, the antenna related information, and the inquiry generated when the inquiry message reaches the valid time. And at least one of inquiry type information indicating whether or not the information is to be made. The method of claim 15, The object to be provided with the channel state information is characterized in that the base station itself or one of the terminals located in the cell. The method of claim 15, The channel state information may include at least one of an idle channel list not occupied by the licensed system and maximum allowed effective isotropically radiared power (EIRP) information for each idle channel. The method of claim 15, The response message may include at least one of type information of the DB server, status information indicating a state of a query, geographical position information of a target to be provided with channel status information, an idle channel list, maximum allowed EIRP information for each idle channel, and valid time information. Apparatus comprising one. In the DB (Data Base) server device that stores the band scheduling information of a licensed system in a Cognitive Radio (CR) based wireless communication system, A control unit for generating channel condition information to be provided to the base station and confirming an effective time which is a time when the validity of the channel condition information is terminated when a query message for inquiring channel condition information is received from the base station; And a communicator for transmitting a response message including the channel condition information and the valid time information. The method of claim 23, wherein And the valid time is a time when a band usage situation of a licensed system is changed with reference to the band usage scheduling information. The method of claim 23, wherein A manager for providing band scheduling information of the licensed system to the controller; And a calculator for calculating a maximum allowable effective isotropically radiated power (EIRP) of an object to be provided with the channel context information for each of the at least one idle channel. The method of claim 25, The controller identifies at least one idle channel by referring to band scheduling information of the licensed system. The method of claim 26, The controller checks the inquiry type information included in the inquiry message before generating the channel situation information, and determines at which point of time the channel situation type is generated according to the inquiry type information. The method of claim 27, The control unit, If the inquiry type information is a value corresponding to the dependent inquiry, it is determined to generate the channel status information after the valid time of the channel status information recently provided to the object corresponding to the geographic location information included in the query message. And when the inquiry type information is a value corresponding to an independent inquiry, determining to generate channel state information at the time when the inquiry message is received. The method of claim 23, wherein The response message may include type information of the DB server, status information indicating a query status, geographic location information of a target to be provided with channel status information, idle channel list, maximum allowed EIRP information for each idle channel, and valid time information. And at least one device.

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